Hi, im very new to sdr and radio in general. I just picked up a RTL2832U and am trying to build my first antenna. I heard the dual planar antenna is a good starting point and am trying to build something similar to this: http://www.wa5vjb.com/references/PlanarDiskAntennas.pdf

I am trying to make one that is a bit more portable and can fold in half when not in use. I thought of attaching two small magnets to the center wire of the coax cable so that as it folds it can connect/disconnect from the top plate. So my main question is, will those magnets interfere with the radio waves at all? and does this sound feasible?

I would say no, consider that many antennas for mobile use are secured to the vehicle via a very powerful magnet. You could confirm this by doing an experiment checking reception and signal strength with vs without magnets.